Method of utilizing natural hydrocarbon gases



Oct. 9, 1934. c. R. WAGNER METHOD OF UTILIZING NATURAL HYDROCARBON GASES Filed March 27, 1950 .Q @uw m...

gru/vanto@ Caryj?. /gzer fr@ WZ/ Patented Oct. 9, 1934 PA'reNr oFFlcE METHOD oF UTILIZING NATURAL mmaocAaBoN GASES Cary R. Wagner, Chicago, Ill., assignor to The Pure Oil Company, Chicago, Ill., a corporation of Ohio lApplication March 27,

4 Claims.

This invention relates to an improved method of utilizing natural hydrocarbon gases. In certain oil producing elds, which are removed from large centers of population, great quantities of natural gas are Wasted, since in such fields there is but limited use for gases of this character. Insuch fields the gas is subjected to compressor recovery operations to extract the liqueflable constituents therefrom and the remaining gases are lai either burned 'as fuel or wasted, and it is therefore an outstanding object of the present invention to subject naturalgases, of the character referred to, to an economical method of treatment for the purpose of producing therefrom larger l percentages of recoverable and liqueable constituents which are admirably suited for use as motor fuels or asblending stock for motor fuels.

'In accordance with the present invention, the latter consists in employing natural gas, or preferably the propane-butane fractions thereof, for the manufacture of a gas containing a high percentage of oleflne hydrocarbons, then stripping this latter gas of its liqueable constituents, and then polymerlzing the olefines into motor fuel fractions by regulated heat and pressure conditions.

For a further understanding of the invention reference is to be had to the following description and the accompanying drawing wherein the figure is a diagrammatic view of apparatus employed in carrying the present invention into practical operation.

Referring more particularly to the drawing, the numeral 1 designates a gas storage tank in which is contained ordinary natural gas of the charvacter produced in oil f'eld operations. This gas, or the propane-butano fractions thereof, obtained through the stabilizationof natural gas, is withdrawn from the tank 1 and is forced by means of a pump 2 through a cracking coil 3 located within the setting of a tube still or converter 4. The gas while passing through the coil 3 may be maintained under a pressure of between 30 and 50 pounds per square inch and during the passage of the gas through the coil a cracking temperature of between 1200 and 1400 F. is attained thereby. This cracking of the gas results in the production therein of oleflnes or unsaturated hydrocarbon compounds and the o cracked gas contains some liquefiable material of high aromatic content. The gases upon being discharged from the coil 3 pass through a cooler 5 and then into a separator 6 at a pressure of about 30 pounds per square inch. Within the separator the liqueable constituents, produced.

1930, Serial No. 439,468

by the cracking operation are removed by way of the pipe line 7 to a storage tank 8.

To further remove the liqueflable constituents from the cracked olefine gases, discharged from the converter 4, the gases which pass overhead from the separator 6 are delivered to a compressor 9 by way of a pipeline '10, and by means of this compressor the gases are placed under super-atmospheric pressure of approximately 200 pounds per square inch -by which the cracked gas is deprived to a high degree of its readily liqueable constituents. From the discharge side of the compressor 9 the recovered liquid constituents, which also contain a high aromatic content, are delivered to the storage tank 8, and may be used there as motor fuels or blending stocks. The gases containing unsaturated hydrocarbons which remain following the compressor operation, as indicated at 9, are then passed to a second pump or compressor 11 wherein the pressure on the, gas is increased to approximately 1000 pounds per square inch. Under this latter pressure the gases are passed through a second coil 12 located in the cooler zones of the converter 4, the coil 12 being heated by the furnace gases developed within the converter after such furnace gases have passed over the coil 3 and been deprived of a considerable portion of their heat. Sufcient heat, however, remains in these Waste gases to heat the extraneous hydrocarbons passing through the coil 12 to a temperature varying between 500 and 950 F. which, while not cracking the gases in the coil 12 to any material extent, provides for the polymerization of such gases so that a large proportion thereof are changed into additive compounds of higher molecular weight. From the polymerization zone of the still, which is formed by the coil 12, the gases pass into a separator 13 under reduced pressure, there being a pressure reducing valve 14 located in the line 15 extending from the coil 12 to the separator 13. From the bottom of the separator 13 the polymerized compounds are withdrawn and delivered to a storage tank 16 as a motor fuel or as a blending stock for such fuels. The distillate produced in the tank 16 is characterized by its high anti-knock value when used as a fuel for internal combustion engines and, in fact, this anti-knock value is sufficiently high to permit it to be employed as a blending stock for inferior motor fuels which possess a low anti-knock value, to the end that the blended fuels will possess a desired anti-knock rating. The xed gases discharged from the separator 13 may be economically used as fuel in the operation of various oil when cracked at 1350 'F. yielded one gallon of liquid constituents and approximately 1100 cubic feet of gas containing substantially 30% of unsaturated hydrocarbons. This gas when compressed to 1000 pounds pressure and subjected to a temperature of 950 F. yielded two and one- 'half gallons of liquid material of the boiling range of ordinary gasoline and'about 800 cubic feet of dry gas.

Example 2.-1000 cubic feet ofa mixture of propane and butane cracked at 1300 F., yielded` two and one-half gallons of liquid product and about 1700 cubic feet of gas containing approximately 50% of unsaturated hydrocarbons. This gas when compressed to 1000 pounds pressure and subjected to a temperature of 900 F. yielded five gallons of the desired liquid product and approximately 1150 cubic feet of dry gas.

By means of the present invention it is possible to convert 50% or more of the propanebutaneV fraction of natural gas into an anti-detonating motor fuel of high rating. As stated, the residue gases furnish fuel for the'furiace and power for the compressor.

vides for marked economy in that it permits of the utilization of a product which is almost valueless to produce a product that is very much in demand, and possesses a correspondingly high economic value.

What is claimed is:

1. Theprocess for producing low-boiling unsaturated hydrocarbon oils from natural gas, which consists in passing natural gas through a cracking zone, heating the gas during its pas-v sage through said zone toA conversion temperatures of between 12 50 to 1350 F.A while said gases are maintained under a pressure of approximatev ly 30 pounds, whereby to produce conversion products of the polymerizing zone from said latter In certain oil lproducing localities the present invention prozone, separating the' unsaturated low-boiling oils formed therein from the remaining fixed gas, and utilizing the same products of combustion which are employed in -the heating of the cracking zone nto a high temperature for heating the polymerizing zone to a lower temperature.

2. The method of treatingl gas composed substantially of hydrocarbons of the methane series whlch'consists in passing the gas through a heating coil in the hotter portion of a furnace wherein the gases are heated to a cracking temperature, passing the cracked gases from the coil Ito a cooler, compressing the gas to a pressure sumcient to liquefy the normally liquid constitutents of the gas without substantially liquefying the ,normally gaseous portion,- separating the liquid portion, further compressing. the gas, passing the compressed gas through a heating coil located in a cooler portion of the furnace wherein the gases are heated to a temperature suiiicient to induce polymerization but insumcient to cause a substantial amount of cracking and recovering desirable liquid fractions from the vapors issuing from lthe second heating coil.

3. The method of treating gas composed substantially of hydrocarbons of the methane series which consists in passing the gas through a coil in the hotter portion of a furnace whereinl the gas is heated to a temperature of between l200 and 1400" F. and cracked, cooling the gas and subjecting it to pressure of approximately 200 pounds per square inch whereby the normally liquid constitutents are liquefied without substantially liquefying normally gaseous constituents, further compressing the separated gaseous constituents to apfractions from the vapors issuing from the second coil. v

4. The method of treating gas composed -substantially of hydrocarbons of the methane series which consists in passing the gas through a heating coil in the hotter portion of a furnace whererin the gases are heated to a cracking temperature, 

